The prior art provides various methods for forming ceramic tiles for architectural applications, and it also provides various glaze compositions which are used to produce the top surface or wear surface of the tile.
Generally, the formation of a ceramic tile involves the steps of forming a raw tile or an unfired ceramic body. Such ceramic bodies are formed from batches of natural or synthetic raw materials such as clay, kaolin, feldspar, wollastonite, talc, calcium carbonate, dolomite, calcined kaolin, oxides such as alumina, silica, corundum and mixtures of the foregoing. Binders and other additives may also be employed to increase the raw mechanical strength of the body.
Once formed, the bodies are fired to form a biscuit that is hard, tough and brittle. In many instances, a glaze composition is applied to the biscuit and given a further firing (double firing) in order to vitrify or sinter the glaze, depending upon the degree of firing. Upon firing the glaze develops a vitreous, transparent or opaque surface that can be glossy or dull (matte), or somewhere in between glossy and dull. Glazes generally comprise one or more glass frits, fillers, pigments and other additives.
In addition to double firing, it is well-known in the prior art to produce tiles by a single fire approach. In the single fire approach, the glaze is applied to the raw ceramic body, and the body and the glaze are then subjected to a single firing operation in order to produce the finished tile.